Examples of 4 ways to generate random passwords with PHP_PHP Tutorial

Using PHP to develop applications, especially website programs, often requires generating random passwords. For example, when a user registers to generate a random password, the user also needs to generate a random password to reset the password.

A random password is a string of fixed length. Here I have collected several methods of generating random strings for your reference.
Method 1:
1. Generate a random integer from 33 – 126, such as 35,
2. Convert 35 into the corresponding ASCII code character, such as 35 corresponding to #
3. Repeat the above steps 1 and 2 n times to connect into an n-digit password

This algorithm mainly uses two functions. The mt_rand (int $min, int $max) function is used to generate random integers. , where $min – $max is the range of ASCII codes, here it is 33-126, the range can be adjusted according to needs, for example, 97 – 122 bits in the ASCII code table correspond to the English letters a – z, for details, please refer to the ASCII code table; chr (int $ascii) function is used to convert the corresponding integer $ascii into the corresponding character.

function create_password($pw_length = 8)
{
$randpwd = ;
for ($i = 0; $i < $pw_length; $ i )
{
$randpwd .= chr(mt_rand(33, 126));
}
return $randpwd;
}
// Call this function and pass the length parameter $pw_length = 6
echo create_password(6);
?>

Method 2:
1. Preset a string $chars, including a – z, A – Z, 0 – 9, and some special characters
2. Randomly pick a character in the $chars string
3. Repeat the second step n times to get a password of length n
function generate_password( $length = 8 ) {
//Password character set, you can add any characters you need
$chars = abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*( )-_ []{}<>~` =,.;:/?|;
$password = ;
for ( $i = 0; $i < $length; $i )
{
// There are two ways to get characters here
// The first is to use substr to intercept any character in $chars;
// The second is to get the character array $chars Any element of
// $password .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
$password .= $chars[ mt_rand(0, strlen($ chars) - 1) ];
}
return $password;
}
?>

Method 3:
1. Preset A character array $chars, including a – z, A – Z, 0 – 9, and some special characters
2. Use array_rand() to randomly select $length elements from the array $chars
3. According to the acquired key name array $keys, extract the characters from the array $chars and concatenate the string. The disadvantage of this method is that the same characters will not be retrieved repeatedly.
Copy the code as follows:
function make_password( $length = 8 )
{
// Password character set, you can add any characters you need
$ chars = array(a, b, c, d, e, f, g, h,
i, j, k, l,m, n, o, p, q, r, s,
t, u, v, w, x, y,z, A, B, C, D,
E, F, G, H, I, J, K, L,M, N, O,
P, Q, R, S, T, U, V, W, X, Y,Z,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, !,
@, #, $, %, ^, &, *, (, ), -, _,
[, ], {, }, <, >, ~, `, , =, ,,
. , ;, :, /, ?, |);
// Randomly select $length array element key names in $chars
$keys = array_rand($chars, $length);
$password = ;
for($i = 0; $i < $length; $i )
{
// Concatenate $length array elements into a string
$password .= $chars [$keys[$i]];
}
return $password;
}
?>

Method 4:
This method This is a new method provided by a netizen after this article was reprinted by Blue Ideal. The algorithm is simple and the code is short. Just because of the return value of the md5() function, the generated password only includes letters and numbers, but it is still a good one. method. Algorithm idea:
1. time() obtains the current Unix timestamp
2. Encrypt the timestamp obtained in the first step with md5()
3. Intercept n from the encrypted result of the second step Just get the desired password
function get_password( $length = 8 )
{
$str = substr(md5(time()), 0, 6);
return $str;
}
?>

Time efficiency comparison
We use the following PHP code to calculate the running time of the above 4 random password generation functions to generate a 6-digit password , and then conduct a simple comparison of their time efficiency.
function getmicrotime()
{
list($usec, $sec) = explode(" ",microtime());
return ((float)$usec (float)$sec);
}
// Recording start time
$time_start = getmicrotime();
//Put the PHP code to be executed here, such as:
// echo create_password(6);
//Record end time
$time_end = getmicrotime();
$time = $time_end - $time_start;
//Output the total running time
echo "Execute Time$time seconds";
?>

The final result is:
Method one: 9.8943710327148E-5 seconds
Method two: 9.6797943115234E-5 seconds
Method three: 0.00017499923706055 seconds
Method four: 3.4093856811523E-5 seconds

It can be seen that the execution time of method one and method two are similar, method four has the shortest running time, and method three has a slightly longer running time point.

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